Light emitting material for use as host dopant in emissive layer for OLEDs

Abstract

A light emitting material comprising a complex of formula (I): (L 1 ) x -M-(L 2 ) y wherein L 1 is a mono-anionic bidentate carbon-coordinating ligand comprising the structural element (II) in a ring system, wherein R1 is a substituent selected from the group consisting of R 1 -1 to R 1 -8, the use thereof as emissive materials in organic light emitting devices, and organic light emitting devices comprising said emissive material.

1 . A light emitting material comprising a complex of formula I
   (L 1 ) x -M-(L 2 ) y   (I)
   wherein L 1  is a mono-anionic bidentate carbon-coordinating ligand comprising the structural element   
       
         
           
           
               
               
           
         
         in a ring system, wherein R1 is a substituent selected from the group consisting of R 1 -1 to R 1 -8, said R 1 -1 to R 1 -8 being defined as follows: 
       
       
         
           
           
               
               
           
         
         wherein: 
         R 2  represents a substituted linear, branched or cyclic alkyl chain having 1 to 20 carbon atoms or an optionally substituted alkoxy group with 1 to 20 carbon atoms, 
         Cy represents a 4 to 7 membered carbocyclic or heterocyclic ring, which may be partially or fully substituted by substituents selected from the group consisting of optionally substituted linear, branched or cyclic alkyl or alkoxy chains with 1 to 20 carbon atoms, 
         L 2  is a non-mono anionic, non-bidentate or non-carbon coordination ligand, 
         M represents a transition metal with an atomic number of at least 40, and 
         x is an integer of from 1 to 3 and y is zero, 1 or 2. 
       
     
     
         2 . The light emitting material in accordance with  claim 1 , wherein the transition metal selected from the group consisting of Re, Os, Ir, Pt, Au, Ru, Rh, Pd, and Cu. 
     
     
         3 . The light emitting material in accordance with  claim 1  wherein the transition metal is Ir or Pt. 
     
     
         4 . The light emitting material in accordance with  claim 1  wherein L 1  has the formula III 
       
         
           
           
               
               
           
         
         wherein: 
         E 1  represents a nonmetallic atoms group required to form a 5- or 6-membered carbocyclic or heterocyclic ring, optionally condensed with additional aromatic moieties or non-aromatic cycles, said ring optionally having one or more substituents, optionally forming a condensed structure with the ring comprising E 2 , said ring E 1  coordinating to the metal M via a sp 2  hybridized carbon, and said ring E 1  comprising the structural element (II) as defined in  claim 1 ; 
         E 2  represents a nonmetallic atoms group required to form a 5- or 6-membered heterocyclic ring, optionally condensed with additional aromatic moieties or non aromatic cycles, said ring optionally having one or more substituents, optionally forming a condensed structure with the ring comprising E 1 , said ring E 2  coordinating to the metal M via a sp 2  hybridized nitrogen; and 
         X represents a coordinating atom selected from the group consisting of groups IVa, Va, and VIa of the periodic system. 
       
     
     
         5 . The light emitting material in accordance with  claim 4  wherein X is selected from the group consisting of C, N, O, S, Se, Te, and P. 
     
     
         6 . The light emitting material in accordance with  claim 5  wherein E 1  is a 2,4-difluorosubstituted phenyl ring of the formula V 
       
         
           
           
               
               
           
         
         wherein the bonds to the heavy metal atom and to E 2  are through neighboring carbon atoms. 
       
     
     
         7 . The light emitting material in accordance with  claim 6  wherein said E 2  is an optionally substituted pyridine ring attached to ring E 1  through carbon atom 2. 
     
     
         8 . The light emitting material in accordance with  claim 1  wherein said ligand L 1  is selected from the group of compounds consisting of L 1 -1 to L 1 -35, said L 1 -1 to L 1 -35 being defined as follows: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
         9 . The light emitting material in accordance with  claim 6  wherein said ligand L 1  is selected from the group consisting of L 1 -1 and L 1 -29 to L 1 -35, said L 1 -1 and L 1 -29 to L 1 -35 being defined as follows: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
         10 . The light emitting material in accordance with  claim 1  wherein L 2  has one of formulae selected from the group consisting of L 2 -1 to L 2 -7, U-1 to U-8, PL, and L 2 -8 to L 2 -27;
 L 2 -1 to L 2 -7 being defined as follows: 
 
       
         
           
           
               
               
           
         
         wherein: 
         A is a substituent selected from the group consisting of halogens —OR 7 ; —SR 7 ; —N(R 7 ) 2 ; —P(OR 7 ) 2  and —P(R 7 ) 2 ; wherein R 7  is a C 1 -C 6  alkyl, fluoro- or perfluoroalkyl group or a C 1 -C 6  alkyl, fluoro- or perfluoroalkyl having one or more ether groups; 
         D is a group selected from the group consisting of —CHR 8 —, —CR 8 R 8 —, —CR 8 ═CH—, —CR 8 ═CR 8 —, N—H, N—R 9 , O, S and Se; 
         R 3 , R 5 , R 6  are the same or different from each other and at each occurrence, represent F, Cl, Br, NO 2 , CN, or a straight-chain or branched or cyclic alkyl or alkoxy group having from 1 to 20 carbon atoms, in each of which one or more nonadjacent —CH 2 — groups may be replaced by —O—, —S—, —NR 9 —, or —CONR 19 —, and in each of which one or more hydrogen atoms may be replaced by F; or an aryl or heteroaryl group having from 4 to 14 carbon atoms which may be substituted by one or more nonaromatic radicals —R′; and a plurality of substituents R′, either on the same ring or on the two different rings, may in turn together form a further mono- or polycyclic ring system, optionally aromatic; 
         R 4 , R 8 , R 9  and R 10  are the same or different from each other and at each occurrence and are each H or an aliphatic or aromatic hydrocarbon radical, optionally substituted, having from 1 to 20 carbon atoms; 
         c is an integer from 1 to 3; 
         d is an integer from 0 to 4; 
         U-1 to U-8 being defined as follows: 
       
       
         
           
           
               
               
           
         
         wherein A, D and R 3  to R 10  have the same meaning as defined hereinbefore with regard to ligands L 2 -1 to L 2 -5; 
         G is a group selected from the group consisting of —CH═CH—, —CR 8 ═CH—, —CR 8 ═CR 8 —, N—H, N—R 9 , and CR 8 ═N—; 
         c is an integer of from 0 to and 
         d is an integer of from 0 to 3, 
         wherein R 8  and R 9  have the same meaning as defined before; 
         PL being defined as follows: 
       
       
         
           
           
               
               
           
         
         wherein X 1  and X 2  are the same or different and are selected from the group consisting of C 1 -C 8 -alkyl, aryl, heteroaryl, which may optionally be substituted by one or more substituents; and 
         L 2 -8 to L 2 -27 being defined as follows: 
       
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein in structures L 2 -8 to L 2 -27 any substituent depicted by a bond symbol may be independently selected from the group consisting of hydrogen, halogen, C 1 -C 8 -alkyl, and an aryl group. 
       
     
     
         11 . The light emitting material in accordance with  claim 1  selected from the group consisting of compounds EM-1 to EM-5, said compounds EM-1 to EM-5 being defined as follows: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein in structures EM-1 to EM-5 any substituent depicted by a bond symbol may be independently selected from the group consisting of hydrogen, halogen, C 1 -C 8 -alkyl, and an aryl group. 
       
     
     
         12 . A method for emitting light, comprising using the light emitting material in accordance with  claim 1  in an emitting layer of an organic light emitting device. 
     
     
         13 . A method for emitting light, comprising using the light emitting material in accordance with  claim 1  as a dopant in a host layer in an organic light emitting device for the host layer to function as an emissive layer in the organic light emitting device. 
     
     
         14 . An organic light emitting device (OLED) comprising an emissive layer, said emissive layer comprising the light emitting material in accordance with  claim 1 . 
     
     
         15 . The light emitting material in accordance with  claim 8  wherein the transition metal is Ir. 
     
     
         16 . The light emitting material in accordance with  claim 10  wherein the transition metal is Ir. 
     
     
         17 . The light emitting material in accordance with  claim 10  wherein the transition metal is Ir, and wherein said ligand L 1  is selected from the group consisting of compounds L 1 -1 to L 1 -35, said L 1 -1 to L 1 -35 being defined as follows: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
         18 . A method for emitting light, comprising using the light emitting material in accordance with  claim 11  in an emitting layer of an organic light emitting device. 
     
     
         19 . A method for emitting light, comprising using the light emitting material in accordance with  claim 17  in an emitting layer of an organic light emitting device. 
     
     
         20 . An organic light emitting device (OLED) comprising an emissive layer, said emissive layer comprising the light emitting material in accordance with  claim 11 .